Razor blades

ABSTRACT

On a razor blade having at least one cutting edge there is provided a coating of a nitride of an alloy of chromium (as herein defined) and optionally a coating of an alloy of chromium (as herein defined). Preferably the outer coating is itself coated with a polymer which improves the shaving properties of the blade, for example polytetrafluoroethylene.

Unlted States Patent 11 1 1111 3,838,512 Sanderson Oct. 1, 1974 1 RAZORBLADES 2,087.051 7/1937 Stargardter 30/346.54

2,452,915 11/1948 Feild [75] Inventor: Mlchae Egham 3,283,117 11/1966Holmes et a1 117/1051 England 73 Assignee: Wilkinson Sword Limited,London, FOREIGN PATENTS OR APPLICATIONS England 1,193,067 5 1970 GreatBritain 30/346.54 1,200,165 7/1970 Great Britain 30/346.54 [22] Filed:Apr. 5, 1972 [21] Appl. No.: 241,446 Primary Examiner-Ralph S. KendallAttorney, Agent, or Firm-Wolfe, Hubbard, Leydig, [30] ForeignApplication Priority Data volt & osann Apr. 13, 1971 Great Britain10649/71 Jan. 29, 1972 Great Britain 4306/72 [57] ABSTRACT 152 US. Cl30/346.54, 1 17/132 CF, 117/75, 011 a razor blade having 111199519119cutting edge there 117 71 M is provided a coating of a nitride of analloy of chro- 15 11 Int. (:1 B26b 21/54 mium herein defined) andOptionally a Coating of 58 Field of Search 117/132 CF, 71, 75 M; analloy of chromium herein Preferably 143 1 5 3; 30 34 54 34 5 3 the outercoating is itself coated with a polymer which improves the shavingproperties of the blade, for ex- 5 References Cited amplepolytetrafluoroethylene.

UNITED STATES PATENTS 13 Claims N0 Drawings 1,930,388 10/1933 Hatfield148/16.6

RAZOR BLADES This invention relates to razor blades and to methods fortheir production.

It is known to provide at least the cutting edge of a razor blade with acoating of certain materials in order to improve the shaving propertiesthereof, for example by increasing their resistance to wear. Materialswhich' have been proposed include certain metals and alloys for examplechromium, or chromium/platinum alloys and certain refractory materialssuch as chromium nitride or chromium oxide.

According to the present invention there is provided a razor bladehaving a discrete coating of nitride of an alloy of chromium (as hereindefined) and if desired a discrete coating of an alloy of chromium (asherein defined) on and/or adjacenta cutting edge thereof.

As used herein the term a discrete coating means a coating of a materialwhich is the same as or different from that of the basic blade and whenof the same material as the basic blade, the coating is additionalthereto. The basic blade is preferably of steel.

The chromium alloys which may be used include those of chromium with atleast one element of Group VIII of the Periodic Table, for example iron,cobalt, nickel or a noble metal, i.e., ruthenium, rhodium, palladium,osmium, iridium or platinum, manganese, rhenium or two or more thereof.Some commercially available alloys may be used.

When iron, cobalt, nickel, or manganese are used in the nitridedchromium containing alloys, it is generally preferred that the alloycontains more than 12 percent by weight of chromium. In the case of thenoble metals, also referred to as precious metals, and rhenium, thechromium preferably constitutes more than 50 atomic percent of thealloy.

As used herein, the term an alloy of chromium is meant to include alloysof chromium with one or more of the specific metals hereinbefore setforth for use in such alloys. Small quantities of at least one furtheralloying element, which may be either metallic or nonmetallic, may bepresent in the alloy in an amount which does not significantly adverselyaffect the shaving properties of the razor blades of the invention, forexample not more than 5 atomic percent. One nonmetallic element whichmay be present, particularly in commercially available alloys, forexample of iron, is carbon.

Particularly preferred chromium alloys are those alloys which arecommonly referred to as stainless and these are generally stainlesssteels or stainless irons. Iron/chromium alloys which may be used shouldin general contain at least 12 percent by weight of chromiumconveniently less than 30 percent by weight. A preferred class ofiron/chromium alloys contain from 16 to 20 percent by weight of chromiumwith the balance being made up, for example, of from 6 to 12 percent byweight of nickel with the remainder being a major proportion of iron andpossibly low concentrations of further alloying elements. One preferredalloy contains about 18 percent by weight of chromium and about 8percent by weight of nickel with the balance iron and a lowconcentration of at least one further alloying element, for examplecarbon.

The term an iron/chromium alloy is used herein to refer generally toalloys containing both iron and chromium and it is intended to includealloys which contain one or more further alloying elements. In general,however, the iron and chromium should together form a major portion ofthe iron/chromium alloy (i.e. at least 50 percent preferably more thanpercent by weight). The further alloying elements may be metallic ornon-metallic. Metallic alloying elements may be selected, for example,from amongst the elements (other' than iron) of Group VIII of thePeriodic Table, e.g., cobalt, nickel, ruthenium, rhodium, palladium,osmium, iridium or platinum, or from amongst other metallic elementssuch as, for example, titanium, zirconium, vanadium, niobium, tantalum,molybdenum, tungsten or manganese.

The relative amounts of iron, chromium and, when present, one or morefurther alloying elements are preferably selected to provide alloyswhich are referred to in the metallurgical art as stainless. Thesealloys include stainless irons and stainless steels.

In general the chromium should be present in an amount of at least 12percent by weight in the iron/- chromium alloys. A preferred class ofiron/chromium alloys for use'in the present invention contains from 16to 20 percent by weight of chromium. However, up to 30 percent by weightor even more chromium may be present.

As stated above, the iron/chromium alloys used in the present inventionshould generally contain a major proportion of iron and chromium. Theother alloying elements, when present will then constitute less than 50percent, preferably less than 30 percent by weight, of the alloy. Carbonis preferably present in only small amounts, e.g., 0.1 percent by weightof the alloy, especially when the chromium content of the alloy is low(i.e. less than about 14 percent).

A preferred class of iron/chromium alloys contains from 16 to 20 percentby weight of chromium with the balance being made up, for example, offrom 6 to 12 percent by weight of nickel with the remainder being amajor proportion of iron and possibly low concentrations of furtheralloying elements. One preferred alloy contains about 18 percent byweight of chromium and about 8 percent by weight of nickel with thebalance iron and a low concentration of carbon.

Examples of iron/chromium alloys which may be used may be selected fromthe alloys listed in Table I below.

TABLE 1 Chemical Composition, "/l Alloy Type Carbon Silicon ManganeseNickel Chromium Molybdenum Others 12% Chromium 0.10 max l.0 max l.0 max0.50 max ll.5/l4.0 0.10% Carbon max. 0.08 max 0.80 max 1.00 max 0.50 maxl2.0ll4.0

Aluminium l27r Chromium, 0.10 max 1.0 max l.0 max 0.50 max ll.5/l4.0(HO/0.30 0.l07 Carbon max. 0.08 max 0.08 max 0.80 max 0.50 max l2.0/l4.00.l0/0.30

Aluminium Carbon max.

TABLE 1-Continued Chemical Composition. l1 A 'lypu Carbon SiliconManganese Nickel Chromium Molybdenum Others 12% Chromium. 0.15 max 1.0max 1.0 max 1.0 max /135 0.1571 Carbon max. 0.09/015 0.110 max 1.00 max1.00 max l1.5/13.5

0.12/0.40 1.0 max 1.0 max 1.0 max l1.5/14.0 014/020 0.80 max 1.00 max1.00 max 11.5/13.5 127: Chromium. 0.1271/0407: ().20/0.28 0.80 max 1.00max 1.00 max /140 Carbon 028/036 0.80 max 1.00 max 1.00 max 12.0/

Sulphur Selenium 0.30 max 1.0 max 1.5 max 1.0 max 11.5/14.0 0.60 max Sor Se 015/030 009/015 1.00 max 1.50 max 1.00 max 11.5/13.5 0.60 max(HS/0.30 127r Chromium Free Cutting 009/015 1.00 max 1.50 max 1.00 max11.5/135 0.60 max 0.15/030 014/020 1.00 max 1.50 max 1.00 max 11.5/1350.60 max 015/030 0.20/028 1.00 max 1.50 max 1.00 max 120/140 0.60 max0.151030 0.12 max 1.0 max 1.0 max 1.0 max 14.0/18.0 17%Chromium 0.10 max0.80 max 1.00 max 0.50 max 16.0/180 0.12 max 1.0 max 1.0 max 1.0 max14.0/18.0 0.80/1.5 17% Chromium Molybdenum 0.10 max 0.80 max 1.00 max0.50 max 16.0/180 090/130 0.15 max 1.0 max 1.0 max 1.0 max 180/230 207:Chromium 0.1 max 0.80 max 1.00 max 0.50 max 18.0/22.0

0.20 max 1.0 max 1.0 max 1.0/3.0 15.0/180 177r Chromium, 27: Nickel0.121020 0.80 max 1.00 max 20013.00 15.0/18.0

- Sulphur 17'7r Chromium. 0.20 max 1.0 max 1.50 max 1.0/3.0 /180 0.60max 0.15/0.30 2'71 Nickel Free Cutting 0.121020 1.00 max 1.50 max200/300 15.0/180 0.60 max 015/030 1771/7'7! 0.15 max 1.0 max 2.0 max6.0/8.0 16.0/180 Chromium- Nickcl 0.12 max 0.20/1.00 0.50/2.00 6.0/8.0/180 1891/97! 0.15 max 1.0 max 2.0 max 8.0/11.0 17.0/200 Chromium-Nickel. 0.15% 0.12 max 0.201100 0.50/2.00 8.0/1 1.0 17.01191) Carbonmax.

Sulphur Selenium 1871/92 0.15 max 1.0 max 2.0 max 8.0/11.0 /190 0.70 maxS or Se 015/030 Chromium- (HS/0.30 Nickel 0.12 max 020/100 0.50/2.008.0/11.0 ITO/19.0 0.70 max Free Culling 0.12 max 0.20/100 GAO/2.008.001110 ITO/19.0 0.70 max 0.15/030 1871/1071 0.09 max 1.0 max 2.0 max8.0/13.0 l7.5/20.0 Chromium- Nickel. 1 0.03 max 0.20/1.00 0.50/2.009.0/12.0 17.5/19.0 009% Carbon 0.06 max 020/100 0.50/2.00 8.0/11.0ITS/19.0 max. 0.06 max 0.20/1.00 0.50/2.00 9.0/11.0 17.5/19.0

1871/12?! 0.10 max 1.0 max 2.0 max 10.0/13.0 17.0/ Chromium- Nickel,0.10% 0.10 max (120/100 0.50/2.00 1l.0/13.0 [TO/19.0 Carbon max.

Titanium 1892/97: 0.12 max 1.0 max 2.0 max 80/110 170/191) SC min.Chromium- Nickel. 0.08 max 0.20/L00 0.50/2.00 9.01120 17.0/19.0 5C/0.70Titanium. 0.12% 0.12 max 010/100 0.50/2.00 8.0/11.0 FLO/19.0 5C/0.90Carbon max.

Sulphur 1891 /9'/( 0.12 max 1.0 max 2.0 max 8.0/1 1.0 ITO/19.0 0.70 max5C min 0.15/0.30 Chromium- Nickc]. 0.12 max 0.20/1.00 1.00/2.00 8.0/11.0 FLU/19.0 0.70 max 5C/0.90 0.15/030 Titanium. Free Cutting Niobium1871/97! 009 max 1.0 max 2.0 max 8.0/110 17.01190 10C min Chromium-Nickel 0.08 max 020/100 0.50/2.00 90/120 17.0/l9.0 MIC/1.00Ni0bium.0.09/(

TABLE I Contmued Chemical Composition,

Alloy Type ilfbOll w 7 Silicon Manganese Nickel Chromium MolybdenumOthers 1771/1071 0.08 max 1.0 max 2.0 max 90/120 16.5/185 1.25/Chromium- Nickel. 1 /254 007 max 020/100 050/200 /110 16.5/185 1.25/1.75Molybdenum 1771/1291 0.09 max 1.0 max 2.0 max /150 160/185 2.0/3.0Chromium- Nickel. 0.03 max 020/100 050/200 /140 l6.5/18.5 2.25/300 2/7(Molybdenum 0.07 max 020/100 050/200 100/130 165/185 2.25/300 1871/12710.011 max 1.0 max 2.0 max 110/150 170/200 3.0/4.0 Chromium- Nickel. 0.06max 0.20/1.00 050/200 /150 ITS/19.5 3.0/4.0 372:7: Molybdenum Titanium1771/1271 0.08 max 1.0 max 2.0 max 110/140 165/185 2.25/30 4C min.Chromium- Nlckel. 0.08 max 020/100 050/200 110/140 165/185 225/3004C/0.60 2 2% Molybdenum Titanium Niobium 177/1271 0.08 max 1.0 max 2.0max 110/140 165/185 2.25/30 10C min. Chromium- Nickel. 0.08 max 020/1000.50/200 11.0/ 16.5/l8.5 2.25/300 10C/l00 ZVzZ Molybdenum Niobium2371/1571 0.15 max 1.0 max 2.0 max 130/160 220/250 Chromium- Nickcl 0.15max 0.20/100 0.50/200 13.0/ 22.0/250 2471/1871 0.15 max 1.0 max 2.0 max160/190 230/260 Chromium Nickel 015 max 020/100 050/200 160/190 230/260237r/2071 0.15 max 1.0 max 20 max 190/230 220/260 Chromium- Nickel 0.15max 020/100 050/200 190/220 230/260 Chromium 070/090 1.5/2.5 1.0 max1.0/2.0 190/210 Silicon-XB 075/085 /225 030/075 l.20/1.70 /210 Tun sten147z/147r 035/050 1.0/2.0 1.0 max 130/150 13.0/150 070 max 2.0 3.0Chromium Nickel, 035/050 1.0/2.0 050/150 120/150 120/150 2.0/3.0Tungsten Nitrogen Sulphur 217/47: 045/060 0.80 max 8.0/110 3.0/5.0200/230 035/055 0.10 max Chromium- Nickelt 048/058 0.25 max 8.0/1003.25/4.50 20.0/220 038/050 0.030 max Nitrogen 048/058 0.25 max 80/100325/450 20.0/220 038/050 0030/0080 Niobium 2l7l/47( 045/060 0.80 max8.0/110 3.0/5.0 20.0/230 2.0/3.0 035/055 0.10 max Chromium- Nickel.048/058 0.45 max 80/100 325/450 20.0/220 2.0/3.0 038/050 0.030 maxNitrogen Niobium 048/058 0.45 max 80/100 325/450 200/220 2.0/3.0 038/0500030/0080 2171/127: 0.10/0.30 1.50 max 2.0 max 100/130 200/230 0.10/0.350.10 max Chromium, Nickel. 0.15/0.25 075/125 1.50 max l0.5/l2.5 20.0/2200.15/0.30 0.030 max Nitrogen Other alloys which may be used include, forexample a chromium/nickel alloy containing about 80 percent by weight ofnickel (commonly referred to as Nichrome) and a chromium/cobalt/nickelalloy containing about 20 percent by weight of chromium, about 40percent by weight of cobalt, about 15 percent by weight of nickel, about7 percent by weight of molybdenum, about 2 percent by weight ofmanganese and 65 about 0.15 percent by weight of carbon with the balancebeing iron (an alloy also known as Elgiloy). Chromium/platinum alloysmay also be used.

The nitrided alloys of chromiii m may be? selected from the nitrides ofthe alloys of chromium hereinbe- 60 fore set forth.

between nitrogen and the alloy metals, e.g., Cr N, Cr N and CrN. Forexample the composition may extend from l to 55 atomic percent nitrogen.

The nitride of the alloy of chromium may form either a single coating ona blade, preferably having an outermost covering of a polymer ofcopolymer which improves the shaving characteristics of the blade, or itmay be one of a plurality of coatings. For example, the alloy ofchromium may be present as a first coating on a razor blade base and thenitride of the alloy of chromium may be present as a coating upon thefirst coatmg.

Where a chromium alloy is used as a first coat of a dual coated blade itis believed to act as an edge strengthening coating. The second coatingis generally chosen to provide a better substrate for adhesion of asubsequently applied polymer coating and/or to facilitatecrystallisation of the polymer coating, upon deposition, in a mannerwhich results in an improved polymer coating.

Two coatings other than a polymer or copolymer may be used and the outerof these two coatings is preferably a nitride of the alloy of chromium.The other coatings which are preferably other than a nitride of an alloyof chromium are preferably metallic, being either of a substantiallypure metal (e.g. chromium) or an alloy thereof, for example aniron/chromium alloy as hereinbefore described. When an alloy coating isused, it is preferably the same alloy as that from which the nitride isderived. For example, the alloy may be an iron/- chromium alloy of thetype hereinbefore described and the nitride coating is then preferablyderived from the same alloy. Similarly alloy and nitrided alloy coatingsmay be derived from chromium/platinum alloys.

The iron/chromium alloy coatings and the nitrided coatings may beproduced by known methods. lonsputtering methods have been foundconvenient although vapour deposition methods may, if desired, be used.

In order to deposit a nitrided coating, a source of nitrogen is requiredto form the nitride and this may, for example be nitrogen alone or a gascontaining nitrogen such as cracked ammonia or air. The gas compositioncan vary widely depending upon the alloy being deposited. For example,the nitrogen or other nitrogencontaining gas may be diluted with aninert gas such as argon, for example with up to 95 volume percent ofargon.

' Sputtering may be directcurr ehtor radio frec uency sputtering and, inthe latter case, sputtering may be direct from a chromium alloy or anitride of a chromium alloy in an inert atmosphere as appropriate. Apressure of from 0.1 to 10 microns of mercury may in general be used toeffect sputtering.

The chromium alloy coating and/or the nitride coating together with anyfurther coating, other than the possible polymer or copolymer coating,should generally have a total thickness of not more than 500A andpreferably from 50 to 450A, advantageously not more than 300A. When aplurality of coatings is used, each coating is preferably from 50 to450A thick.

An outer polymer coating may be applied to the blade having a nitridedchromium alloy coating by known methods. Any of the conventional polymercoatings used to improve the properties of razor blades may be used, forexample those comprising polytetrafluoroethylene or a copolymer ofthiocarbonyl fluoride and tetrafiuoroethylene.

in comparative shaving tests in which razor blades according to theinvention were compared with conventional razor blades, the bladesaccording to the invention were generally preferred since they werefound to give a more comfortable shave from the first shave.

We claim:

l. A razor blade having at least one cutting edge carrying a discretecoating of a prereacted nitride of an alloy of chromium containing atleast 12 percent by weight of chromium.

2. A razor blade as claimed in claim 1, in which said I nitride is anitride of an iron/chromium alloy.

5. A razor blade as claimed in claim 4, in which said nitride coatingand said alloy coating are derived from the same alloy of chromium.

6. A razor blade as claimed in claim 4 in which both alloys of chromiumare iron/chromium alloys.

7. A razor blade as claimed in claim 6, in which the iron/chromium alloycontains from l6 to 20% by weight of chromium.

8. A razor blade as claimed in claim 7, in which the iron/chromium alloycontains from 6 to 12 percent by weight of nickel.

9. A razor blade as claimed in claim 6, in which the alloy containsabout 18 percent by weight of chromium and about 8 percent by weight ofnickel with the balance being a major proportion of iron and,optionally, one or more further alloying elements.

10. A razor'blade as claimed in claim 6, in which the iron/chromiumalloy contains less than 0.1 percent by weight of carbon.

11. A razor blade as claimed in claim 1, wherein a coating of a polymerwhich facilitates shaving with the blade is provided on said nitridecoating.

12. A razor blade having a cutting edge, a first coating of an alloy ofchromium on said cutting edge and a second coating of a prereactednitride alloy of chr0- mium containing at least 12 percent by weight ofchromium on said coating of an alloy of chromium.

13. A razor blade as claimed in claim 12, wherein each discrete coatingis from 50 to 450A thick.

1. A RAZOR BLADE HAVING AT LEAST ONE CUTTING EDGE CARRYING A DICRETECOATING OF A PREACTED NITRIDE OF AN ALLOY OF CHROMIUM CONTAINING ATLEAST 12 PERCENT BY WEIGHT OF CHRMOIUM.
 2. A razor blade as claimed inclaim 1, in which said nitride is a nitride of an iron/chromium alloy.3. A razor blade as claimed in claim 1, having at least one cutting edgecarrying a plurality of coatings, the total thickness of the coatingsbEing not more than 500A.
 4. A razor blade as claimed in claim 1, havinga coating of an alloy of chromium below said nitride coating.
 5. A razorblade as claimed in claim 4, in which said nitride coating and saidalloy coating are derived from the same alloy of chromium.
 6. A razorblade as claimed in claim 4 in which both alloys of chromium areiron/chromium alloys.
 7. A razor blade as claimed in claim 6, in whichthe iron/chromium alloy contains from 16 to 20% by weight of chromium.8. A razor blade as claimed in claim 7, in which the iron/chromium alloycontains from 6 to 12 percent by weight of nickel.
 9. A razor blade asclaimed in claim 6, in which the alloy contains about 18 percent byweight of chromium and about 8 percent by weight of nickel with thebalance being a major proportion of iron and, optionally, one or morefurther alloying elements.
 10. A razor blade as claimed in claim 6, inwhich the iron/chromium alloy contains less than 0.1 percent by weightof carbon.
 11. A razor blade as claimed in claim 1, wherein a coating ofa polymer which facilitates shaving with the blade is provided on saidnitride coating.
 12. A razor blade having a cutting edge, a firstcoating of an alloy of chromium on said cutting edge and a secondcoating of a prereacted nitride alloy of chromium containing at least 12percent by weight of chromium on said coating of an alloy of chromium.13. A razor blade as claimed in claim 12, wherein each discrete coatingis from 50 to 450A thick.